Overtyping control for last line on flat platen machine



March 29, 1955 155;

OVERTYPING CONTROL FOR LAST LINE 0N FLAT PLATEN MACHINE Filed July 30, 1953 INVENTOR. ELMER L. WISE BY @5144 4 ATTORNEV United States Patent OVERTYPING CONTROL For; LAST LINE 0N FLAT PLATEN MACHINE Elmer L. Wise, Farmington, (3011a,, assignor to Underwood Corporation, New York, N. Y., a corporation of Delaware Application July 30, 1953,, Serial No. 371,349

6 Claims. (Cl. 197-2) This invention relates to motor powered flat platen business machines for printing information and has equal applicability to machines known as typewriters or as accounting machines. More particularly the invention 1s concerned with an inexpensive arrangement forpreven tmg overtyping on the last line when the machine has reached the bottom of a page or sheet.

Although the present disclosure refers to a machine having a movable flat platen, such as shown in cope'nding application, Flat Platen Accounting Machine, Serial No. 364,287, filed June 26, 1953 by the present inventor and assigned to the same assignee as the present invention, most aspects of the invention are useful in other flat platen printing machines of well known character where the platen is stationary. The invention is also useful in machines where the platen is optionally stationary or movable, as shown in application Serial No. 262,614, now Patent No. 2,667,956, filed December 20, 195 1 by O. J. Sundstrand et al. and assigned to the same assignee as the present invention.

In a motor-powered fiat platen machine, in which there is relative movement between the platen and a frame member for the purpose of obtaining line spacing, when the platen and frame reach the last line in their relative movement and the end of the last possible line has been typed, an operator may inadvertently type over the last line after the typing mechanism has been returned to the starting position for another line. One of the objects of v the present invention is to prevent this inadvertent ov'ertyping, and to stop the motor which normally drives the platen or frame and powers the typing mechanism, when the end of the last possible line has been reached and the machine calls for another line spacing;

In normal use of a machine of this character, a lever or handle is used to control the reverse movement between the platen and frame from the bottom toward the top of ;a page being typed. This is done through mechanisms driven from the motor which powers the machine. Another object of the present invention is to utilize this same normal reverse control lever 01' handle as a return handle, for initiating automatic drive of the line-spacing parts back to page-starting position even though the driving motor has previously been stopped.

These objects and others are accomplished by providing in the power circuit to the motor, a control switch of special design which is opened by an operating member upon relative movement of parts of the machine when the machine is line-spaced after the last line has been typed. Power to the motor is restored through this same switch but by a different operating member, and a return drive is established through levers controlled by a single movement of the normal line-spacing reverse control handle. This is a relatively inexpensive Way to accomplish the desired results, and one in which the mechanism is kept to a minimum of parts which are dependable in action.

Further objects and details of that which is believed to be novel and this invention will be clear from the following description and claims taken with the accompanying drawing in which is illustrated one embodiment in a fiat platen accounting machine.

In the drawing:

Figure 1 is a partial top plan view of the flat platen machine, with parts shown broken away for clarity in illustration, and in the position they will occupy at the beginning of a page; V

Figure 2 is a side sectional view of the mechanism,

2,705,067 Patented Mar. 29, 1955 ice substantially on the line and in the direction of the arrows 22 of Figure 1, but with the parts in the position they will occupy near the end of a page, and

Figure 3 is 'a perspective view of the special control switch with its cover removed, and showing the members which operate the switch.

There is no need to show or describe the usual keyboard, typing or printing mechanism and other parts of that nature in this machine because they relate only incidentally to the structure of the present invention. It is enough to note that they are present and that lines of alphabetic or numerical characters are typed thereby on a sheet of paper 5 suitably held on a platen 6.

The type bar action, as well as the feeding of the platen in the machine used as an example, is power driven from an electric motor 7, suitably mounted on a portion of the machine in a convenient location. The motor has a shaft 8, constantly driven in a single direction when the motor is operating, and this shaft is connected by suitable gearing in a known fashion to a beveled driving gear 9. This gear is held in constant driving engagement with a .pair of matching bevel gears 11 and 12. The bevel gear 12 is fixed to a driven shaft 13 from which power can be taken to operateparts of the machine not germane to this invention. However, bevel gear 11 is both slidable and r0- tatable with respect to a clutch shaft 14 and therefore will drive the shaft 14 only when the shaft is moved to the left as viewed in Figure 1 and clutch face 15 on the gear 11 is engaged by clutch 16, which is fixedly carried by an extension 17 of the shaft 14. A bearing socket may be formed in the center of gear 12 to support the end of the extension 17 if desired. This clutching and declutching arrangement for shaft 1-4 from the motor drive is used to drive the platen in its return movement, as will later be described.

The platen 6 in the present example is movable with respect to a relatively stationary frame 18, and is guided and supported in its movement as by vertically axled rollers 19 on the platen, which ride against vertical faces on side bars 21 on the frame, and as by horizontally aXled rollers 22 which roll on horizontal surfaces of the frame side bars. At each side edge of the platen a longitudinally extending toothed rack 23 is fixed, and the teeth in each rack engage the teeth in a cooperating gear wheel 24, which is supported by a shaft 25, having a bearing as at 26 in a part of the stationary frame 13. One of the gear wheels is in constant engagement also with a spur 27, fixed to the clutch shaft 14, but the spur may slide with the shaft sidewise with respect to the gear wheel, permitting movement of the shaftwithout disengagement of the connection. Thus, when the motor is running and the clutch face 15 is engaged with clutch 1d, bevel gear 11 will drive clutch shaft 14 and spur 27, and the spur will turn gear wheel 24 to drive rack 23 and platen 6 forwardly downwardly of Figure 1) toward the top line position.

Control of the position of clutch shaft 14 is therefore important, because it governs return movement of the platen. This control is eifected through a spool or roll 28 fixed to the end of the clutch shaft 14. Movement of this spool, and therefore of the shaft, is controlled from an operating handle 29, pivoted as at 31 on a member of the machine frame. The handle, in the position of Figure 1, holds the connected parts in condition so that no driving of the clutch shaft or platen takes place. An operating link 32, pivotally connected at one end as at 33 to the handleand pivotally connected at the other end as at 34 to a clutch shaft operating arm 35, transfers movement of the handle at the side of the machine into movement of the operating arm, to move the spool 28 and the shaft 14 to the left, toward clutch-engaging and driving position, whenever the handle is pulled forward- 1y. The arm 35 is pivoted as at 36 to a bracket 37 on the frame, and this arm carries a shift pin 38 which rides between the flanges on the spool 28. Therefore, when the handle is pulled and the link 32 moves the arm 35 about its pivot, the shift pin will move the spool and clutch shaft toward driving position. Reverse movement of the parts will stop the platen return drive by releasing the clutch.

This control mechanism is held in one or the other of its positions by means of a locating arm 39, pivoted as at 41 to the bracket 37, and spring-pressed toward the pivot connection 34 as by a tension spring 42, secured between anchors on the arm and bracket. Suitable notches or dwells are provided in the edge of locator arm 39 opposite the positions of the two extremes of movement of the pivot connection 34, so that the operating arm 35 and the link 32 and their connected parts will be held in one position or the other. This power-driven return and operating handle is similar to that diclosed in copending application Serial No. 356,494, Flat Platen Typewriter or the Like, filed May 21, 1953 by O. I. Sundstrand et al., and assigned to the same assignee as the present invention.

When it is desired to move the platen short distances in a normal direction, manual control may be provided, like the one shown in the Sundstrand et al. application mentioned immediately above. Briefly, this includes a rotatable shaft 43 which is turned by a handle lever (not shown) on an axis at right angles to the axis of shaft 25. An arm 44 is secured to the shaft 43 and a push link 45 is pivotally connected to the arm. The upper end of the push link extends toward the shaft 25 and is pivotally connected, through an adjustment slot 46, with a crank arm 47. The crank arm 47 is integral or fixed with relation to a pawl operating arm 48, which is rotatable on the shaft 25.

Fixed to the shaft 25 near one end thereof is a circular disc 49 having on its edge a series of closely spaced teeth. Loosely mounted on this shaft near the disc is a pawl carrier arm 51, carrying a pivoted pawl 52 provided with teeth similar to those on disc 49. The pawl operating arm 48 has a pin 53 which fits in a notch provided in the pawl 52.

The pawl operating arm 48 is turned counterclockwise as a result of rotation of the shaft 43 by its handle and consequent lifting of the arm 44, push link 45 and crank arm 47. The pin 53 will thereupon first rock the pawl 52 about its pivot and bring the pawl teeth into engage 'ment with the teeth on disc 49. Further movement of the arm 48 will rotate the disc 49 and the shaft 25 counterclockwise. When the shaft 25 is thus rotated, the gear wheels 24 on the shaft will turn to move the-racks and line-space the platen a short distance rearward (upward of Figure 1) toward the bottom line position.

The present invention comes into play after the platen has been moved to the last possible line position, whether so moved by the mechanisms described immediately above or whether so moved by automatic line-spacing mechanism customary in these machines. In order to prevent overtyping of the last line, the circuit to the motor is interrupted when a line-spacing is attempted after the last line. A switching stud 54 is mounted on a bracket 55 secured to one side edge of the platen, and

this bracket and stud move with the platen in relation to the machine frame.

Supported on the frame, as by a stationary bracket 56, is a switch operating arm 57, pivoted as at 58 to the bracket 56, and carrying a foot 59 which is positioned to be engaged by stud 54 when the platen is moved beyond its last-line position. As shown in Figure 2, the stud will ride under the foot and raise the arm 57, tilting it counterclockwise. This movement of the arm is used to open the circuit to the motor through a switch 61 on the ma-.

chine frame, actuated in this case by an insulating extension 62 on the arm 57.

The switch 61 is made so that not only is it operated to open when the platen passes the last-line position as described above, but also it will be operated to close and start the motor upon forward movement of the platen toward top-line position. Referring to Figure 3, which shows the switch 61 with its cover removed, there is a main movable switch arm 63 in the form of a flat, current-carrying spring, fixedly mounted as at 64 to an insulating base 65. The mounting 64 may also serve as a terminal for the wire 66 leading from a suitable power source, not shown. This spring arm is normally biased toward a relatively stationary switch arm 67, also made of current-carrying material. A preferred material for.

these arms is Phosphor bronze. The switch arm 67 is anchored and has its terminal at 68 on the base block 65, and a wire 69, leading to the motor, is connected thereto. Cooperating contacts 71 and 72 on the switch,

arms 63 and 67 respectively are normally touching be-'.

cause of the spring bias of arm 63, to close th GiiGuit by wire 66 from the power source to wire 69 to the motor.

A free end 73 on switch arm 63 extends outwardly from the switch base 65 in the path of movement of the insulating extension 62 of the operating arm 57 above described. When the extension strikes the switch arm, it overcomes the normal bias and flexes or bends the arm to separate the contact 71 from the contact 72. Because of the relative positions of the stud 54 on the platen and the foot 59 on the switch operating arm, this results in shutting off the motor whenever the platen is moved beyond its last-line position.

Before further typing can be accomplished on the machine, the platen must be moved away from the lastline position, and preferably should be moved back to starting or top-line position. However, because the motor circuit is broken at the switch, there is no power available to accomplish this. Therefore, other means are provided. If an operator pulls the platen 6 forwardly by hand toward the position of Figure 1, the stud 54 on the platen will allow the foot 59 on the switch operating arm to drop and the switch to close the motor circuit. The machine permits power to be restored in this way without driving the platen, because the gear wheel 24 can rotate freely, the clutch shaft 14 being disengaged from its drive.

However, if a return of the platen under power is desired, the reverse lever handle 29 is pulled forward to engage the clutch. This by itself is not enough to drive the platen forwardly because the motor is stopped. Therefore, provision is made to close the motor switch whenever the clutch shaft is shifted to the left. This might be done by any suitable means, but it is preferred to use parts already present for other purposes. Consequently, one end face on the spur 27 on the shaft 14 is used as an actuator for the end 74 of an L-shaped lever 75 which is pivoted as at 76 to the machine frame near the switch. When this lever is moved clockwise by left-hand sliding of the spur 27, it carries with it a second lever 77, which may have a common pivot with the first lever. A tension spring 78, extending between arms on the two levers, allows the second lever to stop when it meets an obstruction, although the first lever may continue its movement. This means that an end face 79 on the end of lever 77 opposite the spring 78 may strike against and move an insulating plunger 81, slidably mounted in the switch base opposite the contact 71 ona, switch arm 63. Because the switch arm is of spring material, sufiicient pressure intermediate the ends of the arm by the plunger 81 will reversely bow the arm until the switch contacts are closed, even though the insulating extension 62 is bearing against the outer free end of the arm in an effort to keep the switch open. After the movement of the plunger stops because of meeting of the contacts, spring 78 will allow overtravel of lever 75. Obviously, as soon as the platen has traveled a short distance, the insulating extension 62 will no longer be bearing on the switch arm and the switch will remain closed and the motor will drive the platen toward top-line position. A stop pin 82 on lever 75 prevents undesirable reverse relative movement with respect to lever 77 beyond a certain point, and these parts may therefore be left free to position themselves during normal machine operation, when not acted upon by the clutch shaft.

In order to stop the return movement of the platen when it has reached the top-line position of Figure l, a platen stop 83 is provided on the platen bracket 55 near the stud 54, and when the platen nears the top-line position this stop will engage the free end 84 of a stop arm 85 pivoted as at 860m the frame between the platen and the operating link 32. The other end of stop arm 85 is slidably and pivotally connected to link 32 as by a shouldered screw 87 on the link and a slot 88 in the stop arm. Therefore, as the platen further approaches the top-line position, the platen stop will rotate the arm 85 clockwise until it has pushed the link 32 and the parts connected thereto to clutch-disengaging position. The platen will thereupon stop its return movement, although the motor will continue to run as above explained. A fresh sheet of paper may then be inserted and typing commenced at the top of the new page on the platen.

In a fiat platen machine in which the platen is stationary and the frame is movable, no essential changes need'bemade to' theacontrol mechanisms here described.

because it is the relative movement between the platen and the frame which actuates the switch and other parts, and not movement of the platen with respect to any other part of the machine.

From the foregoing it will be clear that certain aspects of the invention are not limited to the particular details of construction of the example illustrated, and it is therefore contemplated that various and other modifications and applications of the invention will occur to those skilled in the art. It is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of this invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a machine of the class described, having a frame member and a platen member, one of which members is movable relative to the other between a first-line position and a last-line position, a last-line overtype preventing control comprising an electric motor for driving said machine, a drive from said motor for moving said members relative to each other, a circuit to said motor, a switch in said circuit mounted on one of said relatively movable members, a first actuating arm for opening said switch, a cooperating actuator on the other of said members located in a position for engagement with said actuating arm at the last-line position of said members, a second actuating arm near said switch, a handle for moving said second arm to overcome the action of said first arm for closing said switch, and mechanism operable by said handle for engaging said drive to reverse the direction of movement of the frame and platen members relative to each other to drive them toward first-line position.

2. In a machine of the class described, having a frame and a flat platen slidably mounted in the frame for spacing movement between a first-line and a last-line position, a last-line overtype preventing control comprising an electric motor for driving said machine, a drive from said motor for moving said platen, a circuit to said motor, a normally closed switch in said circuit mounted on said frame, a first movable actuating arm for opening said switch, a cooperating actuator on the platen movable with said platen in a path to engage and move said first arm to open said switch after the last-line spacing of said platen, a second movable actuating arm near said switch for closing said switch, a handle for manually moving said second arm to close said switch against the action of said first arm, and a clutch moved by said handle for connecting said drive to said platen for return movement of the platen toward first-line position.

3. In a machine of the class described, having a frame member and a fiat horizontal platen member, one of said members being slidably movable relative to the other between a first-line typing position and a last-line typing position, means for moving the movable one of said members from first-line to lastline position, motor-driven means for returning said members to first-line position, a motor for driving said machine, and a circuit to said motor, an overtype preventing arrangement for the lastline position comprising a normally closed switch in the motor circuit on the stationary one of the relatively movable members, a first switch operating arm on said switch adjacent the path of relative movement between said members, a switch actuating device on the movable one of said members positioned to engage said switch operating arm and open said switch when the members are in last-line position whereby the motor circuit is interrupted and the drive for the machine is stopped, and an arrangement for restoring said motor circuit and for driving the movable one of said members back to first-line position comprising a second switch operating arm on said switch, a manually operated lever to control said second arm, overcome the action of said first arm and close said switch, driving control linkage also oper ated by said lever establishing a driving connection between the motor and the movable one of said members to return said member to first-line position, and a stop on said movable member engaging said control linkage to break said driving connection when said movable member is in first-line position.

4. In a machine of the class described, having a frame member and a horizontal flat platen slidable in the frame between a first-line typing position and a last-line typing position, a line drive for moving the platen line by line from first-line to last-line position, a reverse drive for returning the platen to first-line position, an electrical motor for driving the machine and electrical circuit including the motor, an arrangement for preventing overtyping of the last line on the platen comprising a switch the circuit mounted on the frame, a spring normally biasing said switch toward closed-circuit position, a first switch operating arm on the switch located adjacent the path of movement of said platen, a switch actuating device on said platen positioned to engage said first switch operating arm, overcome the spring bias and open the circuit when the platen is moved past its last-line position whereby the circuit is interrupted, the motor is stopped and the drive for the machine is disabled, and an arrangement for restoring said circuit and driving the platen back to first-line position comprising, a second switch operating arm on said switch, a hand lever for moving said second arm to close said switch and circuit, a drive control moved by said hand lever to establish reverse drive from the motor to return the platen to first-line position, and a stop projecting from said platen, engaging said drive control and disengaging said reverse drive when the platen reaches first-line position.

5. In a machine of the class described, having a driving motor, a flat platen movable between a first-line typing position and a last-line typing position, and-means for establishing a driving connection between said motor and platen for moving the platen toward first-line position, a control switch for said motor comprising a first switch arm normally biased in a circuit closing direction and carrying a first switch contact, a second switch arm carrying a second contact for cooperating with the first contact to open and close a circuit to the machine motor, a first operating member engageable with said first switch arm and movable to overcome the switch arm bias to open the contacts, a second operating member engageable with said first switch arm and movable to close the contacts while said first arm is in a position to open them, means for automatically actuating said first operating member upon movement of the platen to its last-line position, and means for actuating said second operating member upon establishment of said driving connection for moving the platen toward first-line position.

6. In an electric machine of the class described, having an electric driving motor and a platen movable toward and away from a given typing position, a control switch comprising a flexible spring switch arm with a fixed end and a free end, a first contact intermediate the ends of said arm, a second stationary contact cooperating with the first contact to open and close a circuit to the machine motor, said spring arm being normally self-biased toward contact closing position, a first operating member engageable with the free end of said spring switch arm and movable to flex said arm against its bias to open said contacts, a second operating member engageable with said spring switch arm intermediate its ends and mov' able to reversely flex said arm to close said contacts in spite of the contact-opening engagement and movement of said first operating member, means for automatically actuating said first operating member upon movement of the platen to said given position, and means for removing said first operating member from contact-opening engagement with said spring switch arm upon movement of said platen away from said given position.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,127 Foothorap Apr. 18, 1933 

